You've probably seen this, but here is an index from UNLV library collection of Binnion's pictures,looks like it was Merv and Zsa Zsa:

https://www.library.unlv.edu/speccol/databases/index.php?coll=photocoll&recid=15

"0048 L-R: Zsa Zsa Gabor, security guard, Merv Griffin, Jack Binion. The "Merv Griffin Show" TV show. Guard is holding the $1,000,000 display from Binion's Horseshoe Casino. (c. 1971) "

But the ordering they have listed makes it look like it is a slightly difference picture than the one you have displayed...